Repetition suppression in the medial temporal lobe and midbrain is altered by event overlap.
Repetition suppression in the medial temporal lobe and midbrain is altered by event overlap.
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DOI：
10.1002/hipo.22622
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发表时间：
2016-11
期刊：
影响因子：
3.5
通讯作者：
Preston, Alison R.
中科院分区：
文献类型：
--
作者：
Zeithamova, Dagmar;Manthuruthil, Christine;Preston, Alison R.
重复遭遇同一事件通常会导致内侧颞叶 (MTL) 和多巴胺能中脑的激活减少，这种现象称为重复抑制。相反，遇到与先前经历重叠的事件会导致同一区域的反应增加。这种增加的反应被认为反映了一种联想新奇信号，该信号促进记忆更新以解决当前事件和存储记忆之间的差异。在这里，我们将这些想法结合起来，测试事件重叠是否显着调节 MTL 和中脑反应（即使事件重复且预期），以通过整合促进记忆更新。在接受高分辨率功能性 MRI 时，参与者会反复看到物体对，其中一些物体与其他物体对重叠，其中一些物体包含与其他物体对不同的独特元素。 MTL 和中脑区域对包含独特元素的非重叠对表现出广泛的重复抑制；然而，重叠对的重复抑制程度发生了变化。内嗅皮层、嗅周皮层 (PRc)、中脑和 PRc-中脑连接在重叠对之间显示出与重复相关的增加。值得注意的是，重叠配对的 PRc 激活的增加追踪了推理配对之间关系的能力的个体差异，这是我们记忆整合的行为测量。在海马体中，重叠对之间的激活增加是 CA1 所独有的，与其假设的比较器功能一致。这些发现表明，即使重叠事件本身重复发生，事件重叠也会参与传统上与新颖性处理有关的 MTL 和中脑功能。我们的研究结果进一步表明，MTL（中脑）对事件重叠的反应可能会促进新内容整合到现有记忆中，从而导致跨越经历的关系记忆网络的形成。此外，这些结果为有关 MTL 内部分工的理论提供了信息，表明 PRc 在情景编码中的作用超出了熟悉度处理和项目级识别的范围。
Repeated encounters with the same event typically lead to decreased activation in the medial temporal lobe (MTL) and dopaminergic midbrain, a phenomenon known as repetition suppression. In contrast, encountering an event that overlaps with prior experience leads to increased response in the same regions. Such increased responding is thought to reflect an associative novelty signal that promotes memory updating to resolve differences between current events and stored memories. Here, we married these ideas to test whether event overlap significantly modulates MTL and midbrain responses—even when events are repeated and expected—to promote memory updating through integration. While undergoing high-resolution functional MRI, participants were repeatedly presented with objects pairs, some of which overlapped with other, intervening pairs and some of which contained elements unique from other pairs. MTL and midbrain regions showed widespread repetition suppression for non-overlapping pairs containing unique elements; however, the degree of repetition suppression was altered for overlapping pairs. Entorhinal cortex, perirhinal cortex (PRc), midbrain, and PRc—midbrain connectivity showed repetition-related increases across overlapping pairs. Notably, increased PRc activation for overlapping pairs tracked individual differences in the ability to reason about the relationships among pairs—our behavioral measure of memory integration. Within hippocampus, activation increases across overlapping pairs were unique to CA1, consistent with its hypothesized comparator function. These findings demonstrate that event overlap engages MTL and midbrain functions traditionally implicated in novelty processing, even when overlapping events themselves are repeated. Our findings further suggest that the MTL—midbrain response to event overlap may promote integration of new content into existing memories, leading to the formation of relational memory networks that span experiences. Moreover, the results inform theories about the division of labor within MTL, demonstrating that the role of PRc in episodic encoding extends beyond familiarity processing and item-level recognition.
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影响因子：
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作者：
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